Make VideoFrameType an enum class, and move to separate file and target

Bug: webrtc:5876, webrtc:6883
Change-Id: I1435cfa9e8e54c4ba2978261048ff3fbb993ce0e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126225
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27239}
diff --git a/modules/video_coding/decoding_state.cc b/modules/video_coding/decoding_state.cc
index 1d54063..16266cb 100644
--- a/modules/video_coding/decoding_state.cc
+++ b/modules/video_coding/decoding_state.cc
@@ -100,7 +100,7 @@
     uint16_t frame_index = picture_id_ % kFrameDecodedLength;
     if (in_initial_state_) {
       frame_decoded_cleared_to_ = frame_index;
-    } else if (frame->FrameType() == kVideoFrameKey) {
+    } else if (frame->FrameType() == VideoFrameType::kVideoFrameKey) {
       memset(frame_decoded_, 0, sizeof(frame_decoded_));
       frame_decoded_cleared_to_ = frame_index;
     } else {
@@ -176,7 +176,8 @@
   if (frame->TemporalId() == kNoTemporalIdx ||
       frame->Tl0PicId() == kNoTl0PicIdx) {
     full_sync_ = true;
-  } else if (frame->FrameType() == kVideoFrameKey || frame->LayerSync()) {
+  } else if (frame->FrameType() == VideoFrameType::kVideoFrameKey ||
+             frame->LayerSync()) {
     full_sync_ = true;
   } else if (full_sync_) {
     // Verify that we are still in sync.
@@ -207,7 +208,7 @@
   // A key frame is always considered continuous as it doesn't refer to any
   // frames and therefore won't introduce any errors even if prior frames are
   // missing.
-  if (frame->FrameType() == kVideoFrameKey &&
+  if (frame->FrameType() == VideoFrameType::kVideoFrameKey &&
       HaveSpsAndPps(frame->GetNaluInfos())) {
     return true;
   }